MS is What State? Decoding US Postal Abbreviations

In the realm of United States addresses, the two-letter state abbreviations are ubiquitous, but have you ever stopped to wonder about their origin? Specifically, when you see “MS,” do you know which state it represents? This abbreviation, commonly used by the United States Postal Service (USPS), stands for Mississippi. However, the story behind these abbreviations is rooted in practicality and the dawn of the ZIP Code era.

Prior to July 1, 1963, state names were generally written out in full in addresses. However, the introduction of the five-digit ZIP Code by the Post Office Department (precursor to the USPS) necessitated a change. Early addressing equipment had a character limit of just 23 spaces on the bottom line of an address. To accommodate the new ZIP Code within this constraint, state names had to be shortened.

Initially, in June 1963, the Post Office Department issued a list of state abbreviations. Yet, many of these were still three or four letters long, proving insufficient for the space-saving requirements. By October 1963, a more concise system was adopted: the two-letter abbreviations we recognize today. This streamlined approach made room for the ZIP Code, ensuring efficient mail sorting and delivery. Interestingly, in 1969, a minor adjustment was made when Nebraska’s abbreviation was changed from NB to NE to prevent confusion with New Brunswick, Canada, at the request of Canadian postal authorities.

The table below illustrates how state and territory abbreviations have evolved over time, culminating in the two-letter system that includes “MS” for Mississippi. This system, born from necessity, has become a fundamental part of US address formatting.

Postal abbreviations for states/territories

Sources: 1831, Table of Post Offices in the United States; 1874 and 1943, United States Official Postal Guide; June 1963, Postal Bulletin 20368; Oct. 1963, Post Office Department Publication 59, Abbreviations for Use with ZIP Code.